Knock Sensor or Timing Sensor -- P.S.

[Cat ^. .^ ~]

I forgot to mention . . .for many months the engine icon "idiot 
light" has been coming on and off while driving.

Book says that this is sign that knock regulation is at limit.
Wiring checks out okay.

1.
Does this point to failing sensor or to failing control unit ?

2.
How does one decide which is bad -- sensor or control unit ??

Thanks - Cat



'89 Audi 200 Turbo Automatic (Non Q)
'87 5000

one black cat names Jacques !

http://www.webspawner.com/users/fayskelley/
"Enjoy the edge you are on . . . don't think about the one to come!"  